Latch mechanism



Fatented Dec. 20, 1949 1: UNITED STATES PATENT GFFICE.

LATCH MECHANISM Alfred Muhlhach, Los, Angeles, Qalif.

Application March 12, 1945, Serial No. 5822364" (Cl. 25d-72) 7 Glaims.

This invention relates to latch mechanism and particularly to such mechanism for use in connection with retractable core barrels.

In the drilling of deep wells, especially oil wells, it is common to utilize core drills employing a detachable core barrel which may be removed from the well after a core has been taken, by means of a wire line and an empty core barrel inserted in place thereof. Further, since the cutter which forms the core is subject to rapid wear, it is preferred to mount this cutter on the core barrel, so as to be removable therewith. In this way, drilling may continue without pulling the drill string, until the bit thereon becomes dull, or until other reasons require it. Such an arrangement is shown in my Patent No. 2,263,- 639, issued in November 25, 1941, and entitled "Retractable core barrel.

Means are provided for releasably maintaining the core barrel in proper position in the drill stem as well as forr causing it to rotate the cutter to form the core. It is an` object of this invention to provide improved means for such purpose.

It is another object of this invention to provide such means having a pair of opposed latch members arranged to swing outwardly a substantial distance, whereby the core barrel is securely held in the drill, and unbalanced forces on the core barrel are reduced.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several embodiments of the invention. For this purpose there are shown a few forms in the drawings accompanying and forming part of the present speciiication. These forms will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best dened by the appended claims.

Figure 1 is a section of the latch mechanism, which is shown as supporting a core barrel;

Fig. 2 is a side elevation, partly in section, of the mechanism of Fig. l;

Fig. 3 is a cross section on an enlarged scale taken as indicated by line 3-3 of Fig. 1;

Fig. 4 is a section showing the mechanism in operative position in a drill stem; and

Fig. 5 is a section similar to Fig. 3 but showing a modied form of the invention.

-`Referring to Figs. `1 to 4 of the drawing, the latching device is indicated generally by l and includes a cylindrical tubular body 2, internally threaded at its lower end 3 for attachment to the pin 4 formed in the upper end of a retractable core barrel 5. As clearly shown in Fig. 3, the body 2 has opposed axially extending slots 6 and I through its wall,V in which are accommodated the elongated latch plates A8 and 9, pivotally secured 2 within the body' 21 by a. common pivot pin Ill: ex` tending through the plates near their lower ends.

The arrangement is such that plates B and 9. tend to swing outwardly through their respective slots 6 and l to latehing position. A compression spring IIJ is housed in cooperating grooves l2 and I3 in plates 8 and 9 and urges the plates in op, posite directions about. the pivot ID outwardly of the body 2'. The grooves I2 and I3 are open at. their inner ends. I2-a and I3-a and closed at their outer ends, thus providing oppositely facing seats l2-b and I 3-b for respectively engaging the ends ofthe spring I l.

An operating memberl t5. is provided for controlling the positions of the latch plates 8 and 9. This member I5 is telescoped within the body 2 for relative axial movement. therein and is bifurcated to provide legs i5-a and I 5-7--11 straddling the plates 8 and 9 (see Figs. 2 and 3). A pin I6 extends between the legs I5-a and 15e-b, through openings or slots S-a and 9-c. The pin I6 cooperates with the surfaces 8-b and 9--b of said openings, these surfaces and the pin I 6 thus forming interengaging cam surfacesv on the operating member and on the latch plates.

The operating member l5 has a head Il providing a shoulder I8 which by engagement with the upper end of the body 2 limits movement. of the member 5 inwardly of the body 2. The head I1 is surmounted by a reduced portion |99 with a conical top 20 providing a downwardly directed shoulder 2l adapted to be engaged by an over shot 22. Such over shots are well known and usually include spring urged means such as the pivoted arms 23 (Fig. 1) for engaging under a shoulder, such as 2l upon the over-shot being lowered to engage a tool or other device which it is desired to raise. In this way a lifting force may be exerted which raises the operating member I5 upwardly in the body Z, pin I6 by engage.- ment with the surfaces liv-b and 9-b swinging the latch plates 8 and 9 inwardly from latching position to positions. within the slots B and 'l shown in Fig. l. Upward movement of member l5 in the body 2 is stopped by engagement of pin le with the top s of openings 8-a and 9-a, after which the body 2 moves upwardly with the operating member. In this way upward movement of the over-shot 22 serves to raise the core barrel 5 out of the well. Appropriate means are provided for releasing the arms 23 for detaching the over-shot 22 yfrom the member l5 after removal of the core barrel from the well.

As is well understood, core barrels of the type under consideration are commonly supported in core receiving position by a seat in the core bit, The latch plates 8 and 9 when in latching position serve to maintain the core barrel seated by engagement under a downwardly directed` shoulder!! provided in the drill stem 25 by e ring 26. This ring 26 has a number of axially extending holes for passing circulating fluid. A driving lug 2l is provided in the drill stem 25 which by engagement with oneof the latch plates, as 8, serves to impart rotation of the drill stem 25 to the core barrel 5.

The latch plates 8 and 9 are normally in their v outer or latching positions of Fig. 4. The core barrel with the latch mechanism l attached is lowered in the well in any convenient manner, usually being merely dropped. Upon reaching ring 26, the core barrel passes through it freely, the ring 25 by engagement with the inclined side surfaces of latch plates 8 and 9 forcing the latch plates inwardly and allowing the barrel to continue downwardly to its seat. When the barrel is seated, these plates 8 and 9 are just below the ring 2t and are forced outwardly to latching position beneath the ring by the spring l I.

The use of a pair of latch plates 8 and 9 has important advantages. Thus in the downward movement of the latch mechanism through the ring 2b, there is no unbalanced force exerted by the latch mechanism tending to displace the core barrel from a coaxial position in the drill stem and causing misalinement of the core barrel and its supporting seat. Further, the drill stem can never rotate more than a half a revolution without the core barrels being in driving relation therewith by virtue of engagement 'of the driving lug 2'! with either latch plate 8 or 9.

In the modified form of the invention shown in Fig. 5, a slightly different arrangement is provided, wherein the latch plates are in nested relation. The body 32 is substantially identical with the body 2 of the previously described form with the exception that one of the axially extending slots, as tl, is wider to accommodate a thicker latch plate 32. The latch plate 39 is of U-shaped cross section, the other latch plate 33 being accommodated in the central space 49 of the U. The spring rtl for urging the plates to latching position is accommodated in a recess l2 in plate 38, and is confined between the bottom l2- b of this recess and the bottom 43-19 of the space ii@ in plate 3%. In elevation, the plates 38 and 39 are substantially identical with the plates 8 and 9, being similarly pivotally supported in the body 32 near their lower ends. The plates 38 and 39 are provided with cam slots 3a and 39-a for cooperating with the pin it of the bifurcated operating member I5, all as before.

The inventor claims:

1. In a latching device, a body member having means forming a transverse through sl'ot therein, a' pair of elongated latch members pivoted adjacent their lower ends in said slot forin'depend'ent movement to cause their upper end'pi'irtions'tof extend from said body and form latch surfaces, said members having relatively slidable contact-V ing'faces, there being a groove extending partly across each of said faces and terminating' ata' 4 of U-shaped cross section, the other member being nested therein, said members being movable in opposite directions to cause a portion of each member to project from the body andform a 5 latch surface, and means operatively connected to said latch members for moving said members to and from latch forming position.

3. In a latching device, a body member having a transverse slot therethrough, a pair of mutuallyv overlapping latch members, means pivotally mounting said latch members in said slot to enable portions of said latch members above said pivot means to extend from said body. a spring coniined in the overlapping region of said latch members and seated in said latch members for urging said portions outwardly of said body, and'me'ans engageable with said latchv members for moving said portions inwardly of said body.

4. In a latching device, a body member having a transverse slot therethrough, a pair of mutually overlapping latch members, means pivotally mounting said latch members in said slot to enable overlapping portions of said latch mem-- bers above said pivot means to extend from said body, said latch members havingrecesses 'adjacent each other ai; their overlapping region, a single spring disposed in both of said recesses for urging said portions outwardly of said body, and means engageable with said latch members for moving said portions inwardly of said body.

5. In a latching device as dened in claim 4, wherein said spring is under compression.

6. In a latching device, a body member having" means engageable with said latch members forA moving said portions inwardly of Said body.

7. In a latching device, a body member having a transverse slot therethrough, a pair of mutually overlapping latch members, means pivotally mountingsaid latch members in said slot to enable overlapping portions of said latch members above said pivot means to extend from said v body, said overlapping latch members having opposed transverse grooves in their adjacent side faces, each of said grooves being open lat one end and closed at its other end, a spring in said l opposed grooves having its opposite ends engaging said closed ends ofthe grooves forurging. 'said portions. outwardly of said body, and means engageable with said latch members for` moving said portions` inwardly of said body.

. ALFRED MUHLBACH.

REFERENCES CITED The following referencesare of record inf the v Number Date Drake Sept. 23, 1941 tually overlapping latch members, means pvot- Noble Dec. 26, 1939 Muhlbach ..-'Nov. 25,' 1941- Hoffoss et. al. Oct..12, 1943-? 

